Determination of Henry's Law Constants and Activity Coefficients at Infinite Dilution of Flavor Compounds in Water at 298 K with a Gas-Chromatographic Method

Abstract

Experimental results for Henry's law constants and activity coefficients at infinite dilution of the flavor compounds ethanol, propanol, acetone, 2-butanone, 2-pentanone, 2-hexanone, diacetyl, methyl sulfide, cis-4-heptenal, acetoin, and acetaldehyde in water are reported for a temperature of 298 K. The activity coefficients at infinite dilution were measured with the so-called relative stationary gas−liquid chromatographic method. This method makes use of a reference compound whose activity coefficient at infinite dilution in the solvent (in this case water, which is loaded onto a solid support in a packed chromatographic column) is known. This method is very useful for the determination of activity coefficients of infinite dilution of solutes in volatile solvents, which are difficult to measure in conventional gas−liquid chromatographic methods because of the stripping of the solvent from the column. The reproducibility of the measured values depends on the type of compound and is between ±1 and ±5 %. The choice of a value for the activity coefficient of the reference compounds can cause a systematic error of up to 3 %.